Mark fields transient to satisfy SpotBugs

Co-authored-by: Devin Nusbaum <dwnusbaum@users.noreply.github.com>

Author: jglick

src/main/java/org/jenkinsci/plugins/workflow/log/BufferedBuildListener.java

@@ -52,8 +52,8 @@ final class BufferedBuildListener extends OutputStreamTaskListener.Default imple
     private static final Cleaner cleaner = Cleaner.create(new NamingThreadFactory(new DaemonThreadFactory(), BufferedBuildListener.class.getName() + ".cleaner"));
 
     private final OutputStream out;
-    private final Channel channel;
-    private final Listener listener;
+    private transient final Channel channel;
+    private transient final Listener listener;
 
     BufferedBuildListener(OutputStream out) {
         this.out = out;